1. Field of the Invention
The present general inventive conceptrelates to a spitting device for an inkjet head of an image forming apparatus, and more particularly, to a spitting device for an inkjet head which can prevent printing medium guide ribs formed on a platen from being contaminated by ink ejected from nozzle units during a spitting operation and allows a printing medium to be more stably fed during high-speed printing.
2. Description of the Related Art
An inkjet image forming apparatus can be used as a printer or as a multifunctional device including functions of a copier, a fax machine, and a scanner. When the inkjet image forming apparatus used as a printer, because printing is achieved in a non-impact manner, less printing noise is produced than in a case of a dot printer. Moreover, the inkjet image forming apparatus has advantages in that it can be made compact and light and can perform color printing using a multiple color ink cartridge. An inkjet head ejects fine ink droplets onto a desired position on a printing medium. The inkjet head has a cartridge form, is connected to an ink container, and installed in the inkjet image forming apparatus. The inkjet head uses heat energy or a piezoelectric element as a driving source for ejecting the ink. The inkjet head is fabricated to have high resolution by semiconductor manufacturing methods, such as etching, depositing, and sputtering.
Nozzle units formed on the inkjet head spray ink onto the printing medium. After printing, remaining ink and other substances are attached to a surface of the nozzle units of the inkjet head and harden in holes of the nozzle units over time. Consequently, a defective nozzle, which cannot eject ink droplets during printing, may occur, or an ejecting direction of the ink droplets may be altered, and thus the ink droplets are ejected onto an unintended position of the printing medium. Thus, to keep the surface of the nozzle unit of the inkjet image forming apparatus clean, the inkjet image forming apparatus includes a wiping element that wipes off ink remaining on the surface of the nozzle unit. In addition, to prevent nozzles from clogging, the inkjet image forming apparatus includes a spitting element that removes deposits in the holes of the nozzle units by ejecting ink, and a capping element that prevents ink from drying by covering the nozzle units during a standby state and protects the nozzle units from external particles.
The above wiping element, spitting element, and capping element are commonly referred to as a maintenance element. To miniaturize the inkjet image forming apparatus, a maintenance element of a small size and a simple structure is required.
An array type inkjet head, which includes nozzle units having a length corresponding to a width of printing medium and conveys the printing medium in a lengthwise direction of the printing medium, has a relatively long width. Therefore, a space where the maintenance element is installed is relatively large. During a maintenance operation, the inkjet head does not have to move to a maintenance region, because the wiping element, the spitting element, and the capping element alternately move to the nozzle unit fixed to a predetermined location and perform a predetermined maintenance operation.
The spitting element includes the nozzle units formed on the inkjet head, an ink outlet formed on a platen, and a waste ink container that stores ink which was ejected during a spitting operation and flows thereinto through the ink outlet of the platen.
On the platen, typically, a plurality of conventional printing medium guide ribs are formed to support a back surface of the printing medium. Some of ink ejected from the nozzle unit of the inkjet head during the spitting operation may not flow into the ink outlet but be dispersed around the ink outlet, thereby contaminating the conventional printing medium guide ribs. Moreover, after the spitting operation, the conventional printing medium guide ribs contaminated by the ink may contaminate the back surface of the printed printing medium.
Also, since, the conventional printing medium guide ribs are not installed on a portion where the ink outlet is formed and thus an area of the printing medium guide ribs that support the back surface of the printing medium is reduced, the printing medium is not reliably fed during high-speed printing.